Method for parallel fabrication of nanometer scale multi-device structures

ABSTRACT

Articles exhibiting fabricated structures with nanometer size scale features (nanostructures), typically a device comprising nanostructures of a functional material on or in a substrate of dissimilar material, are produced by a method employing a substrate base or coating and a thin layer serving as a lithographic mask or template, consisting of a self-assembled ordered material array, typically a periodic array of molecules such as undenatured proteins, exhibiting holes, thickness or density variations. It is possible to produce complex structures containing large numbers of nanometers scale elements through a small number of simple steps.

This is a division of application Ser. No. 837,376, filed Mar. 7, 1986,now U.S. Pat. No. 4,728,591.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the formation of structures on a nanometersize scale.

2. Description of the Prior Art

In recent years interest has increased in the fabrication of electronic,optical and/or biomolecular devices of nanometer size (nanometerstructures). An attractive feature, of such molecular size devices isthe vast number that may be packed into a small area, i.e., the highdensity that is possible. Computers which incorporate such devices wouldhave significantly increased memory and speed. The incorporation ofbiological molecules into such devices is also desirable and would befacilitated by the ability to fabricate structures on a nanometer scale.The fabrication of devices on the nanometer level also is desirablesince new physical effects not obtainable for larger size devices beomeimportant. An example is the patterning of surfaces for utilization ofsurface enhanced Raman scattering phenomena.

Current methods of producing such nanometer devices include writing onthe surface of a substrate or on a substrate covered with an electronsensitive resist material with a focused electron beam. This serialmethod of device fabrication is, however, limited by the long timesrequired to produce the vast number of nanometer devices possible insmall areas (i.e., over 10,000 devices in a micron square area)Additionally, conventional methods do not presently offer convenientmeans of incorporating active biological molecules into nanometer sizedevices.

A particularly advantageous method of producing microdevices andmicropatterns consists of lithographic reproduction of an existingpattern from a suitable mask onto the device substrate. Such apreexisting pattern is transferred by placing the mask in proximity tothe underlying substrate. Then the pattern is etched into or applied tothe substrate using a variety of methods including exposure to a beamconsisting of reactive ions, electromagnetic radiation or reactivemolecules The mask is normally produced by ,a serial writing method suchas focusing an electron beam on a suitably sensitive material such as aresist material Current lithographic methods are limited by the size ofthe individual features which can be embedded in a mask, the size of themask as well as the time necessary to produce these masks In particular,currently employed lithographic masks will typically have features whichare micron in dimension whereas nanometer microdevice fabricationrequires masks containing nanometer scale details. While serial writingof such a pattern on a nanometer scale is possible, using known methodssuch as focused electron beams, the necessary time for production ofsuch a pattern is a serious limitation for the practical fabrication ofnanometer devices See, for example, U.S. Pat. Nos. 4,103,064 and4,103,073, Craighead et al, "Ultra-Small Metal Particle Arrays Producedby High Resolution Electron-Beam Lithography", J. Appl. Phys. 53 (11)(Nov. 1982), pp. 7186-7188, Mochel et al "Electron Beam Writing on a20-A Scale in Metal 8-Aluminas", Appl. Phys. Lett. 42 (4) (Feb. 1983),pp. 392-394, Isaacson "Electrons, Ions and Photons in SubmicronResearch", Submicron Research, Cornell University (1984), pp. 28-32.

Attempts have also been made to formulate techniques to fabricatenanometer scale devices "in parallel" wherein a number of devices aremade at the same time in a relatively few number of steps. For example,it has been suggested that large biological molecules may be used as amask to apply a nanometer scale pattern of material on a substrate.Suggestions for the particular large molecule to be employed haveincluded DNA and denatured proteins., See Carter, "Molecular LevelFabrication Techniques and Molecular Electron Devices", J. Vac. Sci.Technol. Bl (4) (Oct.-Dec. 1983), pp. 959-968, Carter, "BiotechnicalSynergism in Molecular Electronics", Nonlinear Electrodynamics inBiological Systems, Plenum Press, pp. 260-273 and Tucker, "Biochips: CanMolecules Compute?", High Technology, Vol. 4, No. 2 (Feb. 1984), pp.36-47 and 79, see particularly p. 46.

SUMMARY OF THE INVENTION

The present invention advances techniques for creating nanostructuresbeyond those techniques known to date as described above. In accordancewith the present invention, arrays consisting of numerous identicalnanometer scale structures are created in a few steps. Suchnanostructures are based on nanometer patterns created by self-assembledtwo-dimensional molecular arrays.

In the present invention, a substrate surface, which can either serve asa passive support such as a carbon film or have intrinsic solid stateproperties used in the device, such as silicon, supports aself-assembled two-dimensional molecular array exhibiting density,thikness and/or chemical reactivity variations. The array may typicallyconsist of two-dimensionally crystallized nondenatured proteins whichretain their native properties of a very regular nature. Alternatively,the array may consist of other non-biological material.

The two-dimensional self-assembled molecular array may be used totransfer a pattern contained in the molecula,r array onto either anunderlying substrate or an overlying coating. In a simple embodiment ofthe present invention, a self-assembled molecular array includes atwo-dimensionally ordered array of holes formed by nondenatured proteinmolecules bound to a substrate base. A functional material to be used inthe nanostructure is deposited onto the substrate surface through theholes. The molecular array is then removed to leave a substrate surfacecovered by a periodic array of islands composed of the material. Aparticular advantage of employing nondenatured protein molecules istheir extremely regular nature.

In another embodiment, the two-dimensional self-assembled moleculararray which is bound to a base support substrate is overcoated with athin film of material to be used in the nanostructure. The film may beof metal, insulator or semiconductor. The film is then irradiated withan ion beam, for example, to replicate the pattern of holes in theunderlying molecular array. In fact, the present invention may beemployed to create improved masks and templates to be used inlithographic production of nanometer structures.

Alternatively, holes through the selfassembled molecular array may beemployed as a pattern for etching the substrate.

Composite devices, biomolecular-solid state heterostructures consistingof biologically active molecules and other functionable materials may beproduced according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of this invention will becomemore apparent and more readily appreciated from the following detaileddescription of the presently preferred exemplary embodiments of theinvention taken in conjunction with the accompanying drawings, of which:

FIG. 1 is a schematic diagram of a nanostructure including aself-assembled two-dimensional molecular array used as a template for anoverlayer;

FIG. 2 is a schematic diagram of a nanostructure consisting of aself-assembled two-dimensional molecular array used as a mask for thedeposition of additional material on a substrate;

FIG. 3 is a schematic diagram of a nanostructure consisting of aself-assembled two-dimensional molecular array used as a mask forremoving material from a substrate;

FIG. 4 is a schematic diagram of the electron density of theself-assembled two-dimensional molecular array from Sulfolobusacidocaldarius superimposed with the results of metal deposition;

FIG. 5 is a schematic diagram of one possible finished nanostructureaccording to the present invention;

FIGS. 6A-6H schematically illustrate the process for forming thestructure of FIG. 5;

FIG. 6I represents a nanostructure according to another embodiment ofthe present invention;

FIGS. 7A-7D schematically illustrate the method of forming ananostructure in accordance with yet another embodiment of the presentinvention; ,

FIGS. 8A-8D schematically illustrate the steps of forming a structureaccording to the present invention with a multilayered substrate havingmaterial deposited therein and having an overlying pattern of materialcommensurate with the deposits in the substrate; and

FIG. 8E is a schematic illustration of a nanostructure according to thepresent invention with a multilayered substrate having deposits thereinand an overlying pattern of material incommensurate with the deposits inthe substrate.

DETAILED DESCRIPTION Of THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS

A fundamental structural unit that forms the basis of all embodiments ofthis application and is illustrated in FIGS. 1-5 includes a substrate 10supporting a self-assembled two-dimensionally ordered molecular arraycontaining thickness, density or chemical reactivity variations in aspatial pattern having a characteristic dimension of 1-50 nanometers. Ofcourse, a pattern of variations in thickness may very well be a patternof holes extending through array 12.

Substrate 10 may be made of a passive supporting material such as amolecularly smooth amorphous carbon, crystalline mica or graphite or afunctional material to be used in the ultimate nanodevice such assilicon. The substrate base may also consist of a multilayer compositesuch as layers 10a illustrated in FIGS. 8A-8E. Multilayered substrate10a may include silicon coated by a thin insulating layer of silicondioxide or other material, for example.

In some cases, the substrate base may be a well defined area which ispart of a larger base support. For example, the base may contain amicropattern consisting of a thin layer of conductive material such asaluminum which is deposited by conventional lithographic methods. Inthis case, array 12 could be bound selectively to specific areas on base10 delineated by the micropattern. This can be accomplished by using avariety of conventional methods which serve to activate the specificareas delineated by the micropattern so that they bind array 12. Forexample, array 12 could be made of a material that normally carries anelectrical charge and which is attracted to the patterned conductinglayer through application of a voltage differential between this layerand a second electrode placed above substrate 10. Alternatively, apattern which is lithographically transferred to a substrate base usingconventional methods can be selectively activated by using glowdischarge. In this case, surrounding areas which do not contain themicropattern would be prevented from developing an attractive chargebecause they would be coated with an insulating layer.

Self-assembled array 12 can be conventionally produced using avariety.of protein molecules including hemocyanin,,cytochrome oxidase,porin from the E. coli outer membrane, acetylcholine from nicotinicend-plate receptors, rhodopsin from photoreceptor membranes and in somecases are found to occur, in nature such as in the S-layer fromSulfolobus acidocaldarius or the purple membrane from Halobacteriumhalobium. Approximately 1000 distinct two-dimensional crystallizableproteins are known. A general method for production of such aself-assembled protein array is described by Keegstra and van Bruggen,"Electron Microscopy at Molecular Dimensions" Springer-Verlag, New York(1980), pp. 318-327.

A second example of array 12 involving the membrane protein rhodopsin isgiven by B.L. Scott et al, "Two-Dimensional Crystals inDetergent-Extracted Disk Membranes From Frog Rod Outer Segments (ROS)"Bio. Phys. J. Vol. 33, (1981) p. 293a. Self-assembled membrane arrays 12are typically 5-20 nanometers in thickness and normally have an overalldiameter between 0.1 and 1 micron. It is possible, however, to formlarger membranes using established procedures such as membrane fusionwhich consists of adding a detergent such as cetyltriammonium bromide(CTAB) to a suspension of membranes and then incubating at roomtemperature for several days.

Examples of array 12 which contain an ordered pattern of through holesinclude the two-dimensional array formed by hemocyanin, a respiratoryprotein from the spiny lobster Panulirus interruptus, according to themethod of Keegstra and van Bruggen, supra, and the S-layer which isnaturally found in the facultatively sulphur oxidizing microorganism,Sulfolobus acidocaldarius and isolated according to the method of Michelet al, Electron Microscopy at Molecular Dimension, Ed. by W. Baumesiterand W. Vogell, Springer-Verlag (1980), p. 27. Numerous other examples ofarray 12 which form naturally or can be formed using known methodsinclude those formed from the proteins cytochrome oxidase, porin andconnexon.

Bacteriorhodopsin in the purple membrane of Halobacterium halobium andrhodopsin isolated from frog or bovine retinas form arrays 12 which havea pattern of two-dimensional density and thickness variations. Thetwo-dimensional crystals formed from ribosomes, well known in theliterature, form a biomolecular assembly containing both protein andnucleic acid which may be used as array 12.

Array 12 may also have chemical reactivity variations spatiallydistributed thereover Examples of materials which may be used for array12 exhibiting chemical reactivity variations include protein moleculeswhich exhibit catalytic activity or act as a coenzyme for catalyticactivity. Array 12 of purple membrane formed from bacteriorhodopsinmolecules exhibit such a spatially varying chemical reactivity since itacts as a light-driven proton pump. Hence, a local pH gradient will becreated at the site of each bacteriorhodopsin molecule duringillumination of the entire array with light of 570 nm wavelength. Thislocal pH gradient could be used to activate pH sensitive reactions inthe molecules of an overlayer thereby producing a structural patternwithin the overlayer on a nanometer scale dimension. A large number ofreactions are known which are pH sensitive including reactions involvingmolecules contained in many commercially available pH sensing papers.

Array 12 can also consist of the surface layer of a three-dimensionalcrystal. For example, most three-dimensional crystals formed fromprotein molecules consist of large void spaces filled with water whichcomprises up to 80% of the total volume of the crystal. The top surfacelayer exhibits a large variation in contour which is ideal for acting asa template in the same manner as a monolayer two-dimensional crystal asdescribed herein. Examples include crystals formed from the proteinmolecules lysozyme and hemoglobin.

Additionally, many examples of two- and three-dimensional array 12 ofnon-biological origin exist which are useful in the present invention.For example, zeolites from a class of crystalline materialscharacterized by periodic arrays of nanometer dimension holes may beemployed in the present invention, as illustrated by Wright et al,"Localizing Active Sites in Zeolitic Catalysts", Nature, Vol. 318, p.611 (1985). These non-biological arrays could be used as single crystalsurfaces or in the form of thin films, grown epitaxially as unit cellmonolayers on a crystalline substrate. Microscopic colloidal particlesof uniform size are another non-biological example useful as array 12.Such an array is formed by slowly altering the chemical properties of acolloidal particle suspension in contact with substrate 10 to be coatedin such a way as to cause particles to come out of suspension anddeposit on the surface of substrate 10. In an aqueous suspension ofpolymer spheres, for example, the salt concentration can be increased.When this, process is done slowly, ordered arrays of particles ofdiameters from 5 nm to about 1000 nm can be deposited on the surface.

Various techniques may be employed to bind array 12 to substrate 10 orarray 12 may be formed on substrate 10 in situ. Binding can beaccomplished electrostatically which is typically achieved by treatingsubstrate 10 chemically or by placing substrate 10 in a glow dischargechamber. Array 12 is then applied as an aqueous suspension of membranefragments on substrate 10 which is subsequently dried by evaporation,blotting with an adsorbant medium or by mechanical shaking.Alternatively, array 12 can be bound using a binding layer betweensubstrate 10 and array 12 which can consist of an application ofpolylysine or another molecule which binds preferentially to substrate10 and array 12.

To chemically bind array 12 to substrate 10, substrate 10 may bechemically treated or coated in such a way as to promote the binding ofarray 12. For example, a substrate of carbon may be coated with anadsorbed molecular layer of the cationic polyamino acid poly-l-lysine inorder to bind array 12 with an anionic surface. Alternatively, forexample, the anionic polyamino acid poly-l-glutamate will bind cationicarray 12 to substrate 10. For example, substrate 10 may be placed in avacuum and exposed to a mild plasma etch (glow discharge) prior to theapplication of the polyamino acid. A 10% solution of the polyamino acidis applied to substrate 10 and left to incubate for several minutes.Substrate 10 is then washed with distilled water and air dried. Array 12is then applied to the coated substrate 10.

Array 12 may be bound to substrate 10 by electrical means when substrate10 is selected to be electrically conducting. Conducting substrate 10may be placed in contact with an aqueous suspension of two-dimensionalordered membrane sheets which carry a surface charge. Applying anelectric field between substrate 10 and a second electrode in contactwith: the suspension can both orient the sheets with one sidepreferentially facing substrate 10 and move the membrane sheets ontosubstrate 10. For example, purple membrane has been shown to exhibitordering in suspension in applied electric fields. See, Keszthelyi,"Orientation of Purple Membrane by Electric Fields" Methods inEnzymology, Vol. 88, L. Packer (Editor), pp. 287-297.

Related orientational effects can be achieved by magnetic fields.

Electro-chemical means may be employed to bind array 12 to substrate 10.As an example, substrate 10 may have a patterned Ta/W film on onesurface with an ordered array of holes in the Ta/W film exposing acarbon base. An oxide film is rapidly produced on the Ta/W film byapplying 0.1 N NaOH to substrate 10 while applying a voltage between themetal film and the NaOH. This is accomplished by connecting the grid onwhich substrate 10 sits to the positive terminal of a battery andconnecting the negative terminal to the NaOH solution via a smallelectrode. A resistor in series with the grid controls the current draw.In this fashion, an oxide layer is produced on the metal, while no oxideis formed on the exposed carbon holes. After deposition of the oxidelayer, the grid is washed, dried and then glow discharged in order tomake the carbon hydrophilic, for the subsequent adsorption of adifferent molecule, such as the protein ferritin. The ferritin ispreferentially adsorbed on the exposed carbon holes and not on the metaloxide layer surrounding them.

It is also possible to crystallize array 12 directly on the surface ofsubstrate 10 using the properties of the substrate to promotecrystallization. This is accomplished using methods of two-dimensionalprotein crystallization well-known in the literature. An example givenby Keegstra and van Bruggen, supra, involves the assembly oftwo-dimensional arrays of Panulirus interruptus hemocyanin. A small dropof hemocyanin protein in a 10 millimolar (mM) sodium acetate buffer isplaced on an electron microscope grid having a parlodion-carbonsupporting substrate: The grid, with the protein solution on top, isfloated on a 50 mM sodium acetate solution for a time from 30 minutes toseveral hours at 4° C. with the specimen supporting substrate 10 actingas a membrane for dialysis. Then, the grid is washed and dried.

From the basic structure of array 12 on base 10, a number of alternativeembodiments can be created. For example, as illustrated in FIG. 1,overlayer 14 may be applied on top of array 12. Overlayer 14 may consistof a thin layer typically 1-2.5 nanometers thick of a material selectedfor its ultimate function in subsequent steps in the nanometer structurefabrication. For example, when pattern 16 in array 12 includes holes,pattern 16 may be transferred into overlayer 14 by ion milling to formholes 18. As will be explained below, overlayer 14 may then be removedand used as a nanometer mask for further steps in the nanodevicefabrication. In this case, the material for overlayer 14 may be chosenfor its flexibility and structural integrity. Alternatively, overlayer14 may comprise a functional material in the ultimate nanodevice and bechosen for its optical/electronic properties.

A specific example of the embodiment illustrated in FIG. 1 will now beprovided. In this embodiment, array 12 is the crystalline proteinaceouscell wall surface layer (S-layer) from the thermophilic bacteriumSulfolobus acidocaldarius a sulfur-oxidizing microorganism whose naturalhabitat is hot acidic springs. The S-layer consists of 10 nm thickmonolayer periodic array of a single glycoprotein having a molecularweight in the range of 140-170 kdaltons. Specimens of purified S-layershow an array of protein dimers arranged as shown in FIG. 4, a basis ofthree dimers on a two-dimensional triangular lattice having a 22 nmlattice parameter. The three-dimensional structure is porous, theprotein occupying 30% of the volume within the 10 nm thick sheetcontaining the S-layer.

Substrate 10 in this embodiment of the nanostructure device consists ofa 30 nm thick amorphous carbon film which provides a molecularly smoothsurface. The carbon film is deposited on an electron microscope grid 3millimeters in diameter using conventional methods. The S-layers areemployed in the form of aqueous suspensions (12 mg/ml) of primarilymonolayer crystalline fragments of varying size up to 0.5 microndiameter. Adsorption of the S-layer to the carbon substrate isaccomplished by exposing the substrate to a mild plasma etch (glowdischarge) in order to remove organic contaminants and render carbonsubstrate base 10 hydrophilic. A drop of S-layer suspension is thenplaced in contact with substrate 10 and rinsed with double distilledwater. Excess water is drawn off with filter paper and the preparationair dried.

Overlayer 14 is then deposited by evaporation. In this embodiment,overlayer 14 is a thin layer Ta/W which is chosen because of its finegrain. Application of overlayer 14 is accomplished by e-beam evaporationof 80% tantalum and 20% tungsten (by weight) at 2×10⁻⁶ torr at roomtemperature at an incident angle of 40 degrees from the normal tosubstrate 10. This produced an average overlayer thickness of 1.2 nm asdetermined by a quartz crystal monitor and grain sizes of 2-3 nm asdetermined by electron microscopy.

To pattern overlayer 14 to assume pattern 16 of thickness or densityvariations in array 12, overlayer 14 is exposed to an argon ion mill fora short period of time in order to punch holes corresponding tovariations 16 in array 12.

Substrate 10 in this example may consist of a large variety ofmaterials. For example, for the purpose of electrical contact, substrate10 may be fabricated from a conductor such as aluminum. Alternatively,substrate 10 may consist of a layered structure such as a conductorcoated by a thin insulator such as aluminum and aluminum oxide or asemiconductor material such as a P-doped silicon. To provide a guide forbinding array 12, or as a suitable surface for crystallization,substrate 10 may consist of a patterned surface produced by conventionalscanning beam methods or by other methods described herein.

Alternatively, a liquid surface may be utilized since it is well knownthat many arrays such as purple membrane can be layered on the surfaceof a liquid such as water. All of the formation techniques describedherein may be carried out with an array supported by such a liquidsurface. One advantage of such a substrate 10 is the ease by which thepatterned nanostructure is removed from liquid substrate 10.

Thus, some proteins, in particular biomembrane based systems, are easierto grow as large single crystals with the proteins and a lipid matrix atan air-water interface. Once formed, a two-dimensional protein crystalat an air-liquid interface could be used as a template fornanopatterning an evaporated metal overlayer 14 as has been describedabove. Patterned metal layer 14 could then be transferred to a solidsubstrate by the usual techniques employed to deposit surfactant(Langmuir-Blodgett) films. Alternatively, overlayer 14 once patterned,could be removed from two-dimensional array 12 by immersing substrate 10in a fluid and floating it on the air-fluid interface as is routinelydone for carbon-platinum freeze-fracture replicas.

Overlayer 14 may be part of a larger pattern formed using conventionalmethods of integrated circuit ,fabrication. In this case, a suitablemask formed from a resist is used to allow deposition to occur only inthe desired areas including the area overlying array 12.

Overlayer 14 may also consist of a thin layer of material which has beenpatterned using the methods described herein. For example, a thin layermetal which has been patterned into a metal screen containing nanometersized holes can be produced as described herein. This layer can beselectively bound directly over a two-dimensional self-assembled array12 to serve as overlayer 14.

Alternatively, a nonpatterned overlayer 14 may be deposited on an array,and then coated with a second array 12. The second array is used topattern the layer using masking techniques to be described and thenremoved. In a second fabrication step, the underlying array serves as atemplate for further patterning as described above. The two arrays couldbe commensurate, producing a periodic structure, or incommensurate,producing a modulated structure, as will be described below with respectto FIGS. 8A-8E.

A variety of overlayers 14 may be patterned using arrays 12 astemplates, for example thin metal films as has been described above. Asother examples, overlayer 14 itself may be a layered structure producedby multistage evaporation or by chemical treatment, e.g., oxidation, ofan initially homogeneous film. A first layer of Ta/W may be followed byPt, for example.

Instead of using array 12 as a template for producing a patternedoverlayer 14, array 12 may be used as a mask for applying material on orin substrate 10 or.removing material from substrate 10. In FIG. 2, array12 is employed as a mask for forming deposits 20 on substrate 10. InFIG. 3, mask 12 is employed to control the removal of material fromsubstrate 10 forming pits 22. In the embodiment of FIG. 2, array 12advantageously has a pattern of through holes allowing penetration ofatoms or molecules through array 12 to substrate 10. In the embodimentof FIG. 3, density or thickness variations in array 12 can betransferred directly into substrate 10 utilizing penetrating X-ray orelectron beams which then react with substrate resist material. To formpits 22, an agent may be applied to the assembly which reacts directlywith substrate 10 or is activated by the additional exposure of apenetrating beam such as visible light. Alternatively, the removal oralteration of the composition of base material 22 might occur throughelectrical conduction of ions through the channels formed in array 12.

The embodiment illustrated in FIG. 5 is a more detailed version of thatillustrated in FIG. 1 in that it consists of array 12 on substrate 10with overlayer 14 having holes 18 therein. In this embodiment, holes 18have a diameter of approximately 15 nm arranged on a triangular latticewith 20 nm periodicity. Holes 18 are formed in overlayer 14 which isbest characterized as a lattice or screen consisting of two intersectingperiodic sets of metal strips. Film 14, which is approximately 1 squaremicron in area, is part of larger micropattern which has been fabricatedusing conventional methods. Conducting electrod,e material 24 isdisposed adjacent to array 12 and overlayer 14 to complete the assembly.

The method of forming the embodiment of FIG. 5 is illustrated in FIGS.6A-6H. First, as illustrated in FIG. 6A, the 1 square micron area ofexposed carbon layer 10 to which the S-layer array 12 is bound isfabricated by depositing a photoresist material 26 onto a largercarbonffilm and then exposing and developing this resist usingconventional prior art microdevice fabrication methods in the area wherethe nanostructure is to be formed. A hydrophobic resist material ischosen to minimize binding of the S-layer to the surface of resist 26.Then, array 12, consisting of the S-layer is disposed in the space onsubstrate 10 layed open after removal of the exposed photoresist. Then,as illustrated in FIG. 6B, a one nanometer thick layer of Ta/W isdeposited as described above with respect to FIG. 1. That is, overlayer14 is deposited using evaporative beam techniques applied at a 40° angleto the normal. It should be noted that the undeveloped layers ofphotoresist 26, i.e., those areas where the carbon layer of substrate 10is not exposed, will also be coated with the Ta/W.

In FIG. 6C, holes 18 are formed in overlayer 14 using argon ion mllingat normal incidence. In this example, a 2 KV beam of 0.2 ma/cm² isemployed for 25 seconds This has the effect of transferring spatiallyordered pattern 16 in array 12 to overlayer 14., Note that the size ofthe screen formed depends on the time of exposure to the argon ionmilling For example, thinner sized screen strips and larger holes can beproduced by increasing the exposure time to ion milling from 25 to 30seconds. Conditions, of course, will vary depending upon the thicknessof metal film 14 and exact specifications of the ion mill.

In addition to ion milling, holes 18 can be formed by X-ray irradiation,electromagnetic irradiation, electron beam irradiation, particle beamirradiation, etching, chemical removal, solvent removal, plasmatreatment or any combination of these various techniques.

In FIG. 6D, the areas of substrate 10 which had been covered byphotoresist 26 and film 14 are removed by exposing and developing thephotoresist using conventional methods.

In FIGS. 6E-6H, conductors 24 of micron dimension are fabricated onsubstrate 10 leading to and from the nanostructure device usingconventional methods In FIG. 6E, photoresist layer 28 is placed over theentire area of substrate 10 including areas covered by the 1 nanometerthick Ta/W film 14 which contains the nanometer screen pattern. A wirepattern is exposed on photoresist 28 and upon developing, thephotoresist is removed from areas where the wire pattern occurs in FIG.6F. In FIG. 6G, conducting metal layer 30, such as aluminum, isdeposited. In those areas where the wire pattern has been developed,metal 30 will directly coat carbon base 10. In step 6H, photoresist 28and overlying metal 30 are removed, leaving only conducting metal layer24 to form,the wires.

Although the nanostructure described was produced on a carbon layer, itis to be understood that a similar method can be used to producenanometer patterned devices on other useful solid state surfaces such assilicon. In addition, while the fabrication of only a single nanometerpatterned microdevice was described, a similar multistep method could beused to fabricate in parallel many such nanodevices which are arrangedin a complex pattern comprising an electronic or optical integratedcircuit.

Although conventional electrodes have been utilized in the example ofFIGS. 6A-6H which directly connect to the nanostructure array,alternative methods of interacting directly with such a patterned arrayare also possible. For example, each individual nanostructure can beaddressed using a scanning tunnelling microscope probe. In the case ofoptically sensitive material, entire arrays can be addressed with afocused laser beam.

The device as illustrated in FIGS. 1 and 5 can be considered amicrosubstrate comprising a base substrate, a lithographic mask ortemplate material containing an ordered nanometer scale pattern andoverlying material to which the patterned nanometer scale detail hasbeen transferred. The method described in FIGS. 6A-6H demonstrates thatsuch a microsubstrate can be used to produce a microdevice based on thenanometer patterned array. In contrast to conventional methods forproduction of micropatterns, the methods thus far described and thearticles produced therefrom.allow significantly smaller patterns to beproduced. For example, conventional photo-lithographic methods forproduction of integrated circuits result in microdevices typically onemicron square area. The embodiment described in FIGS. 6A-6H results inthe patterning of several thousand nanostructures in a one micron squarearea.

In addition, as described with respect to FIG. 6A-6H, conventionallithography can be used in conjunction with the microsubstrate toproduce a nanometer pattern within the normally unpatterned area used toproduce conventional micro devices. The present invention also offerssignificant advantages over more conventional methods of writingnanometer size patterns on a substrate surface with an electron beam.The present invention allows for parallel production of large numbers ofnanometer structures thus offering a significant decrease in the time itwould take to produce the same microdevices with the serial writemethod, for example with a scanning electron beam.

FIGS. 7A-7D illustrate a manner in which the structure of FIG. 2 andother useful structures can be formed. As illustrated in FIG. 7A, array12 is formed on substrate 10. Then, as illustrated in FIG. 7B, a threenanometer thick layer 33 on array 12 and pro3ections 32 in holes 16through array 12 is formed using an evaporative beam at normalincidence. This structure may be created in the same manner asillustrated in FIGS. 6A-6B except that the metal is applied at normalincidence. Layer 33 and projections 32 may be a metal, such as Ta/W orany other material.

In FIG. 7C, array 12 is lifted off with layer 33 to leave projections 32deposited on substrate 10. Projections 32 obviously have the samepattern as holes, 16 in array 12. Array 12 can be lifted off using anumber of techniques which break up the organic biomolecular array anddo not effect projections 32. For example, array 12 may be exposed to adetergent solution such as 5% SDS (sodium dodecylsulfate), proteolytenzymes which specifically degrade protein, or acid such as HCl, or acombination cf these solvents. Patterning of micron dimension electricalconducti g wires which lead to and from the nanometer array ofprojeotions 32 can be accomplished using conventional micro fabricationmethods similar to those described with respect to FIGS. 6E-6H.

An additional step may also be desirable as illustrated in FIG. 7D tofill the area between projections 32 with a second dissimilar material34 such as an insulator. This can be accomplished by evaporating such amaterial directly onto the surface of the device containing thenanometer array.

Similarly, after fabrication in accordance with FIGS. 6A-6H, adissimilar material 36 may be evaporated onto the assembly to fill holes16 in array 12 as illustrated in FIG. 6I.

Although evaporative beam techniques have been employed in theembodiments above to apply material, material can also be applied usingmolecular or atomic beam epitaxy, sputtering, chemical deposition,electrophoretic deposition, crystallization, binding, using,an adhesiveor any combination of these materials.

As has been mentioned above, the substrate may be layered as illustratedin FIGS. 8A-8E. Layers of subst,rate 10a may be single crystals of mixedatomic layers as formed by molecular beam epitaxy. These crystals arestacks of planar nanometer thick sheets, parallel to the crystalsurface, each composed of a few atomic layers, with alternatingcomposition. Heterogeneous semiconductor and metallic materials havebeen formed this way. As substrate base 10a, these materials arestructured on a nanometer scale in the direction normal to the planarsurface (Z-direction). Further nanometer structuring of these materialsis possible in and on the planar surface (X,Y directions). A method forstructuring such material is illustrated in FIGS. 8A-8E. In FIG. 8A,array 12 and overlayer 14 are formed on layered substrate 10a inaccordance with the techniques described above. Overlayer 14 may then beemployed as a mask for etching or ion milling pits 38 in substrate 10aas illustrated in FIG. 8B. Pits 38 may be etched in a selected number oflayers of substrate 10a.

As illustrated in FIG. 8C, pits 38 may be filled with material 40 byevaporation, producing a composite material structured in threedimensions. For example, material 40 may be nanometer dimension metalareas embedded in layered semiconductor substrate 10a.

A three-dimensionally patterned material produced as just described maythen be a substrate for further nanofabrication steps using the methodsdescribed herein. For example, as illustrated in FIG. 8D, material 42may be applied to the surface of material 40 through holes 18 inoverlayer 14. As a more concrete example, in FIG. 8,C, material 40 maybe one semiconductor material embedded in another semiconductor material(or the same material of differing impurity concentrations or doping) ofsubstrate 10a. Then, in FIG. 8D, protein array 12 can be readsorbedcommensurate with material 40 and used in a second fabrication step inwhich material 42 is applied through holes 18 in layer 12. For example,nanometer dimension p-type semiconductor regions 40 may be formed in ann-type semiconductor layer of substrate 10a. Then, the assembly could becovered by nanometer dimension metal islands 42.

Alternatively, instead of readsorbing an array 12 commensurate withmaterial 40, different protein crystal which give incommensurateregistration with the patterned surface could be used as illustrated inFIG. 8E. This would serve to break the periodicity of the nanometerpattern to produce more complex Moire-like structures that vary in aregular way but on a larger length scale as the surface is traversed.

A nanometer patterned device produced using the methods illustrated inFIGS. 6A-6I, 7A-7D and 8A-8E and similar devices which can be patternedusing modifications of these procedures may be employed to create anumber of extremely useful devices. For example, a basic pattern for anumber of superconducting and quantum interference devices is based onthe fabrication of arrays of micron-sized metal islands spaced by aninsulator, or the complementary structure consisting of a continuousmetal sheet with a periodic array of insulating holes. The method forproduction of both of these structures on a nanometer length scale, isdescribed in FIGS. 6A8E and additional mpdifications described below.

A particularly advantageous structure in accordance with the presentinvention includes an array of superconducting nanometer size metalislands separated by nonsuperconductors. In this case a metal such asNb₃ Sn which becomes superconducting at temperatures below 18° K aredeposited as described with respect to FIGS. 7A-7C. A nonsuperconductinglayer such as a normal metal is then deposited as shown in FIG. 7D.Electrodes are deposited on the surface of the microsubstrate base atthe edges of the nanometer patterned array to enable current to flow inthe plane of the film, parallel to the rows of islands.

In this configuration, each row of islands behaves as a seriesconnection of an SIS (superconductor-insulator-superconductor) junction.Such a junction is recognized as a device for the detection oflong-wavelength radiation with high sensitivity. Conventionalmicrofabrication of such SIS junctions is based on the use ofconventional lithographic integrated circuit fabrication methods. Thisresults in array junctions with dimensions on the scale of microns.

A major advantage of patterning such an array of nanometer size SISjunctions is the enhanced dynamic range which increases as the square ofthe number of junctions connected in series in the array. In addition,the parallel connection of rows reduces the array inductance and therebyreduces the effects of junction and voltage threshold heteroge,neitywhich would normally result if the SIS junctions vary in size. A secondadvantage of such a microdevice which acts as a sensitive microwavedetector is the ability to place several thousand of these device arraysin a small area less than 1 cm square. Hence, spatial detection ofmicrowave field gradients is facilitated.

A second advantageous device made in accordance with steps similar tothose illustrated in FIGS. 6A-6I is a nanometer pattern consisting of asuperconducting screen 14 containing holes 18. One advantage of such anetwork of holes 18 is realized when it is connected to electrodes whichenable current to flow in the plane of the screen. It is generallyrecognized that in this case an increased current carrying capacityoccurs relative to a continuous superconducting film due to the abilityof the holes to trap flux vortices. This is a desirable property of asuperconductor since without flux pinning it is recognized thatsuperconductors will exhibit flux instability, dissipation, temperaturerise and quenching.

A desirable property of such a two-dimensional network of holes on thenanometer size scale in a metal is the appearance of quantuminterference effects. In particular, since an electron mean free path ina metal of greater than 10 nm is generally achievable at room ormoderately low temperature, there will exist quantum interferenceeffects in a nanometer network film fabricated from normal metal usingthe method of FIGS. 6A-6I or similar methods without going to extremelylow temperatures. Such a property is advantageous for use, in a magneticfield or current detection device since the quantum interference effectwill be sensitive to applied magnetic fields. Such quantum interferenceeffects form the basis for the use of conventional SQUID(superconducting quantum interference devices) which are fabricated onthe micron scale using conventional microfabrication techniques. Theadvantage of the present invention is that a large number of smallerquantum interference devices can be fabricated in parallel. Furthermore,due to the size of these devices the quantum interference effects willbe realized without going to extremely low temperature and without theuse of superconducting materials.

Another embodiment of the present invention involves the fabrication ofa nanometer patterned array consisting of a screen and projections eachconsisting of dissimilar semiconducting materials such as doped andundoped GaAs. Such a nanometer patterned array would constitute atwo-dimensional superlattice. One-dimensional superlattices consistingof alternating nanometer layers of semiconductor material have beenfabricated using prior-art-methods and are the basis for several newclasses of opto/electronic devices. It is recognized that the ability tocarry out nanostructure fabrication on surfaces and the extension of thesuperlattice concept into two and three dimensions will lead topotential applications which cannot be realized with one-dimensionalsuperlattices. These arise from additioal modifications of theelectronic band structure with quantization in two and three dimensions.The advantage of the methods illustrated in FIGS. 6A-8E and similarmethods for producing two-dimensional superlattices is increased speedand flexibility of fabrication over conventional methods.Three-dimensional superlattices may also be fabricated using thetechniques described with respect to FIGS. 8A-8E in order to deposittwo-dimensional superlattices on top of each other.

An additional advantage of the basic method of this invention lies inthe ease by which a nanometer composite pattern of immobilizedfunctional molecules and an additional material such as a semiconductorcan be fabricated. One starting point for fabrication of such acomposite material is the structure illustrated in FIG. 6H. In thiscase, nanometer holes 16 formed are filled with a specific molecule 36with a desired functional property as illustrated in 6I. Such propertiesmay include enzymatic activity, sensitivity to electromagnetic andparticle radiation, fluorescence, electrical, magnetic, thermalconduction, chemical reactivity and mechanical.

As a specific example, a nanometer size memory array utilizing thebiomembrane protein, bacteriorhodopsin, which is found in the purplemembrane of Halobacterium halobium, which exhibit several of theaforementioned properties, may be employed. This embodiment is formed byfollowing steps illustrated in FIGS. 6A-6H, which results in fabricationof the article shown in FIG. 5. It is to be understood that a variety ofmaterials may be chosen from which to fabricate patterned screen 14which contains a, network of nanometer size holes 18. This structure canbe employed to make a biosensor by incorporating active biomolecules 36in nanometer dimension holes 16. For example, enzymes (which bindmolecules to be sensed) can be attached by a variety of chemicalmodifications of substrate 10 or subsequent to the hole fabrication.Enzymes which exhibit a change in dipole moment or charge flux in thedirection normal to the substrate surface will induce a voltage betweensubstrate 10 and perforated metal 14. This voltage can be read out viathe deposited wires if they are separated from the substrate (conductingin this case) by an insulating layer.

In this application, the periodic nanopatterning offers two bigadvantages: (1) It allows the sensor molecules to occupy sites betweenthe two conductors, i.e., between the perforated metal film and theconductive substrate. (2) The holes allow free access to the sensormolecules from fluid adjacent to the perforated surface.

The binding of bacteriorhodopsin (bR) molecules inside the nanometerpattern of holes 16 can be accomplished using a variety of methods whichdepend on the nature of the device substrate base 10. For example, amethod for selective binding of protein molecules such as bR on a carbonsubstrate has been described. Zingsheim, H.P. Zingsheim, ScanningElectron Microscopy, Vol. I, pp. 357-364 (1977), was able to demonstratethe inhomogeneous binding characteristics of a patterned surface forprotein adsorption. In this experiment an insulin-coated carbon film wasused as a target onto which 3-4 nm side contamination lines at spacingsof about 50 nm were drawn using electron beam writing, by a STEM.Subsequent to the beam writing, two-dimensional surface charge patternscan be produced if the specimens are immersed in electrolyte solutions.Specimens prepared in this manner contain sufficient information todirect molecules of the protein ferritin to predetermined adsorptionsites with a precision of 2-5 nm.

Alternatively, antibody molecules which selectively bind bR and can beproduced using conventional methods in pure form can be firstimmobilized inside holes 16. In this case, a suspension of bR trimerswhich retain the functional properties of bR molecules found in theintact purple membrane are bound selectively by the antibodies in thevicinity of holes 16. This later method of selectively binding bR can beeasily applied to other molecules for which an antibody can bedeveloped. This includes almost all proteins including those possessingbiocatalytic properties.

An additional method of filling holes 16 with bR 36 involvesself-assembly of the native purple membrane lattice using conventionaltwo-dimensional crystallization methods which involve the incubation ofa detergent solution of bR and lipid molecules over the surface of thedevice shown in FIG. 5. Typically, intact purple membrane fragments aresolubilized in a 0.2-1.0% solution of cetyltriammonium (CTAB) detergentwhich should be used in pure form. The solution is then slowly dried byreverse,phase evaporation over a period of several days. It is importantto render holes 12 hydrophilic by exposing the article of FIG. 5 to aglow discharge in order to promote the bR solution to enter holes 12. Inaddition, large holes over 20 nm are advantageous in order toaccommodate several bR trimers.

Ferritin molecules as material 36 may be selectively bound in nanometerholes 16 formed by patterned screen 14. The ferritin can be made topreferentially adsorb to free holes 16 in pattern 12 as opposed to metalstrips 14 by for example, a surface coating of the polyamino acidpoly-l-lysine. The poly-l-lysine may be applied before a carbonsubstrate 10 is glow discharge treated and before the adsorption oftwo-dimensional biomembrane 12. Alternatively, the poly-l-lysine may beapplied prior to metallization and ion milling of biomembrane 12. Ineither case, the poly-l-lysine will be exposed, after the millingprocedure, only at metal free holes 16. The cationic polylysine willthen serve to bind the anionic ferritin, resulting in the ferritin asmaterial 36 being bound preferentially to metal free holes 12 and notmetal strips 14.

In addition to bare ferritin, the above nanoheterostructure formationcan be accomplished using ferritin which has been previously conjugatedto another biological molecule. As an example of a ferritin conjugate,ferritin can be conjugated to concanavalin A, which is a lectin, thatis, a plant protein with a high affinity for certain sugar residues.

It is possible to conjugate ferritin to an antibody (or immunoglobulin).As an example, it is possible to form a ferritin.-conjugated antibodydirected against the protein spectrin. This ferritin-conjugated antibodycan be selectively adsorbed on a patterned template 12, thus forming ananohete,rostructure. Then, spectrin may be deposited on the surface ofthe nanoheterostructure to strongly bind at those sites containing theferritin-conjugated antibody.

A nanoheterostructure can also be formed comprising a solid statepattern 12 with preferential adsorption of a biological molecule 32 or36 having catalytic activity. Enzymes are complex proteins which serveas reaction catalysts. So a nanoheterostructure could be formed with anenzyme bound at specific sites on patterned template 12. For example,the enzyme invertase could be bound at select sites and the sugarsucrose will be hydrolyzed at these catalytic sites.

A nanoheterostructure can also be formed by adsorbing a non-biologicalmaterial, for example, colloidal gold to ordered pattern 12. Moreoverthis colloidal gold can be bare or can be readily conjugated toimmunoglobulins (antibodies), antigens, protein A, or other biologicalmaterials.

Yet another structure in accordance with the present invention is atwo-dimensional array 12 of the. nanometer size elements whichconstitute a high-density information storage medium. This propertystems from the ability of bR to behave as a multistate switch. Since thebR molecule functions as a light driven proton transport element, it issensitive to electromagnetic radiation as well as changes in theelectrical potential across it. It has been demonstrated thatapplication of a potential can result in alterations in the s,tate of bRas determined by a shift in its normal adsorption maximum from 570 nm tored-shifted adsorption maxima typically near 610 nm. Production of sucha shift requires total potentials across the 5 nanometer transverselength of the bR molecule of less than 300 mV. Such a potential can beapplied locally to a hole 16 filled with bR molecules using a vacuumtunnelling and scanning microscope probe as has been developed byBinnig, Rohrer et al, "7×7 Reconstruction on Si(III) Resolved in RealSpace" Phys. Rev. Ltr. Vol. 50, p. 120 (1983) and references citedtherein. The ground voltage level can be determined by substrate base 10which can be fabricated from a conducting material. In this case screen14 should be fabricated from an insulator. In order to enhance chargingabove the bacteriorhodopsin the molecules can be decorated withnanometer conducting metal particles using published procedures. Eachindividual memory element can be addressed by scanning the tunnellingprobe with subnanometer precision over the two-dimensional ordered arrayof holes 16 filled with bR until the hole for which information is to bewritten or read is selected. Writing consists of applying a voltage tothe bR molecules in holes 16, thereby altering their state which isaccompanied by an adsorption change. Reading can be accomplished byprobing changes in potential developed across hole 16 by use of thetunnelling probe. Such molecular switching can be achieved using, thismethod in any protein having multiple states with different dipole orcharge distributions.

Additionally, nanoheterostructures may be formed in which the,orderedpattern consists of a pattern of islands 32 to which pattern ispreferentially adsorbed a conducting polymer 34 (see FIG. 7D). Anexample of such a conducting polymer is poly(para-phenylene), or PPP,and its derivatives. Another conducting polymer for nanoheterostructureformtion is polypyrole.

As an alternative to prefetentially adsorbing a single conductingpolymer to an island 32 of the pattern, it is possible to produce adeposition of the polymers such that a single polymer will connect two(or more) islands 32. This is accomplished, for example, with polymershaving binding sites along its length rather than just at its terminus,or with polymers having binding sites at both ends and its length iscommensurate with the spacing of islands 32. More generally, the numberof monomers forming the polymer could be adjusted so that the length ofthe polymer chain is compatible with the lattice spacing of islands 32,or some multiple of the lattice spacing.

It is to be understood that there are numerous other advantageousdevices which can result from the binding of functional molecules to ananometer patterned array. Examples include surface catalytic arrays,nanometer templates for crystallization and polymerization, bimolecularsensors, surface enhance Raman scattering detectors and substrates,pyroelectric detectors and digital films for lithography and imaging.

Although a few exemplary embodiments of this invention have beendescribed in detail above, those skilled in the art readily appreciatethat many modifications are possible in the preferred embodiment,swithout materially depatting from the novel teachings and advantages ofthis invention. Accordingly, all such modifications are intended to beincluded within the scope of this invention, as defined by the followingclaims.

What is claimed is:
 1. A method of forming a pattern on a nanometerscale comprising the steps of:binding to a substrate surface aself-assembled two-dimensionally ordered material array forming atwo-dimensional spatial pattern of at least one of thickness, densityand chemical reactivity variations, said pattern having a characteristicdimension of 1-50 nanometers, forming at least one overlayer on saidarray; and forming a two-dimension, nanometer scale pattern of holes insaid overlayer which is determined by said pattern in said array.
 2. Amethod of forming a pattern on a nanometer scale comprising the stepsof:binding to a substrate surface a self-assembled two-dimensionallyordered array of nondenatured protein molecules said two dimensionalarray forming a two-dimensional spatial pattern of at least one ofthickness, density and chemical reactivity variations, said patternhaving a characteristic dimension of 1-50 nanometers; and transferring atwo-dimensional nanometer scale pattern formed from said at least one ofthickness, density and chemical activity variations onto said substrate.3. A method of forming a pattern on a nanometer scale comprising thesteps of:binding to a substrate surface a self-assembledtwo-dimensionally ordered array of nondenatured protein molecules saidtwo dimensional array forming a two-dimensional spatial pattern ofholes, said holes having a dimension of 1-50 nanometers; and applyingmaterial to an assembly of said array and said substrate to formprojections in said holes bound to said substrate.
 4. A method offorming a pattern on a nanometer scale comprising the steps of:bindingto a substrate surface a self-assembled two-dimensionally orderedmaterial array forming a two-dimensional spatial pattern of at least oneof thickness, density,and chemical reactivity variations, said patternhaving a characteristic dimension of 1-50 nanometers; and removingmaterial from portions of said substrate corresponding, to said spatialpattern to form pits.
 5. A method of forming a pattern on a nanometerscale comprising the steps of:binding to a substrate surface aself-assembled two-dimensionally ordered material array forming atwo-dimensional spatial pattern of at least one of thickness, densityand chemical reactivity variations, said pattern having a characteristicdimension of 1-50 nanometers; forming at least one overlayer on saidarray; forming a two-dimensional nanometer scale pattern ins aidoverlayer, which is determined by in said array; and connecting at leastone of said array and said overlayer to at least one conductiveelectrode.
 6. A method as in claim 4 further comprising the step offilling said pits with material different from said substrate
 7. Amethod as in claim 6 wherein said substrate is multi-layered and saidpits extend down into at least two layers and said method furthercomprises the steps of:applying material on the surface of saidsubstrate in accordance with a two-,dimensional spatial pattern having acharacteristic dimension of 1-50 nanometers.
 8. A method as in claim 6wherein said substrate is multi-layered and said holes extend comprisingthe steps ofreplacing said array with another self assembledtwo-dimensionally ordered array forming another two-dimensional spatialpattern of holes different from said pattern of said array, said anotherpattern having a characteristic dimension of 1-50 nanometers; andfilling said holes in said another pattern with material extending abovesaid substrate
 9. A method as in claim 1 further comprising the step ofapplying conductive electrodes to at least one of said overlayer andsaid array.
 10. A methgd as in claim 1 further comprising the step ofapplying material different from said array and said overlayer throughsaid holes in said overlayer.
 11. A method as in claim 1 or 2 furthercomprising the final step of removing said array.
 12. A method as inclaim 1 further comprising the step of removing said overlayer.
 13. Amethod as in claims 1, 2, 3 or 4 wherein said binding of said arrayincludes the step of electrically binding said array spatiallydifferentiated part of said substrate surface.
 14. A method as in claim13 wherein said electrically binding step includes the steps of:applyinga conducting layer to said spatially differentiated part of saidsubstrate; and charging said conducting layer, said array being bound.in areas defined by said charging.
 15. A method as in claims 1, 2, 3 or4 wherein said array binding step includes the step of charging thesubstrate surface by exposing the substrate surface to charged partcles,plasma, atoms or molecules.
 16. A method as in claims 1, 2, 3 or 4wherein said array binding step includes the step of adding adhesive tosaid substrate surface to bind said array to said substrate.
 17. Amethod as in claims 1 3 or 4 wherein said array binding step includesthe step of crystallizing said array in situ on said substrate surface.